Over the years, many systems have been used for introducing a catheter into a blood vessel using a wire to guide the catheter into the vessel. One system involves the use of a hollow introducer needle having an over the needle catheter mounted thereon. After the bevelled tip of the introducer needle is inserted into the blood vessel, as indicated by "flashback" (i.e., the flow of blood from the punctured vessel through the hollow needle and out the proximal end thereof), a wire guide is fed through the hollow introducer needle and advanced until the desired length of the wire guide is within the blood vessel. The catheter is then advanced of of the introducer needle onto the wire guide and into the blood vessel.
Another system is shown in U.S. Pat. No. 4,417,886 entitled "Catheter Introduction Set" ("the '886 Patent"), which discloses a catheter introduction set for the introduction of an over the needle catheter into a relatively small diameter blood vessel. The set includes a hollow needle, an over-the-needle catheter, and a wire guide with the needle and wire guide contained in a single unit. The catheter is carried on the hollow needle and the wire guide is located within the hollow needle. After puncturing the vessel using the needle, blood flashback is visualized in the clear hub of the introducer needle (to provide a positive indication that the needle is actually within the vessel) and the wire guide is then advanced through the hollow needle and into the blood vessel. The over-the-needle catheter is then advanced off of the needle, onto the wire guide and into the vessel, after which the inserter unit (the introducer needle and the wire guide) is removed from the inserted catheter and may be thrown away. The placed catheter is connected to a stop cock, injection cap or to an appropriate connecting tubing. Although the set described in the '886 Patent has enjoyed success, aspects thereof require improvement, particularly with respect to the size of the system, the desirability of instantaneously visualizing flashback and the ever increasing requirement of developing patient care systems which minimize contact by healthcare workers with patient fluids including, principally, blood.
A catheterization system which exhibits some of the advantages of the '886 Patent is shown in U.S. Pat. No. 4,894,052 of Jan. 16, 1990 entitled "Flash Detection In An Over-The-Needle Catheter With A Restricted Needle Bore" ("the '052 Patent"). In the '052 Patent, a translucent over-the-needle catheter is mounted over an introducer needle having a bevelled tip. The distal end of the catheter is provided with a tight fit with the distal end of the needle, while the inside diameter of the catheter is dimensioned in relation to the outside diameter of the needle to provide an annular flashback chamber therebetween, which chamber is closed at its distal end and open at its proximal end.
The hollow needle is connected to the annular flashback chamber by an access port formed in the needle near the distal tip of the catheter such that, upon penetration of the vessel by the needle, there will be rapid visualization of flashback of blood into the annular flashback chamber. To facilitate the insertion of the catheter into the vessel, a guide wire is positioned within the hollow needle. After flashback blood enters the annular flashback chamber via the access port, the wire guide is advanced into the vessel and the over the needle catheter is then moved off the needle and along the guide wire into the blood vessel. Advancement of the wire guide into the vessel serves to obstruct the access port, thereby limiting the free flow of flashback blood into the annular chamber.
Upon placement of the catheter in the vessel, the inserter unit, which includes the syringe, the introducer needle and the guide wire, is separated from the placed catheter a which point the catheter may be appropriately connected for its intended purpose. Although early flashback can be visualized in this prior art system, there are a number of disadvantages including overall size, the need to use a construction much like a hypodermic syringe with its complexities, etc.
Still other prior art systems are available for inserting catheters utilizing wire guide techniques and providing for flashback visualization to permit confirmation of the proper placement of the introducer needle into the blood vessel. One such system is identified as the Arrow EID Catheter which includes a self-contained J spring wire guide which is inserted through a thin wall introducer needle to assist advancement and accurate placement of the catheter in any central vein. In this system, flashback is visualized by the flow of flashback blood through the introducer needle and about the J shaped spring wire guide to an aspiration syringe. In the Arrow EID Catheter, the wire guide is initially in its retracted position. The vessel is punctured by the introducer needle, and blood flashback indicates successful entry into the vein. After stabilization of the introducer needle, the spring wire guide is advanced as required into the vessel and the catheter is moved forward along the spring wire into the vessel.
A significant problem with many prior art designs is that they are not bloodless. For example, some flashback chambers are designed so that blood within the chamber leaks out and may then come in contact with nurses and physicians. Other designs permit blood leakage through the wire guide insertion assembly. Still other designs permit leakage at the needle hub. As can be readily ascertained by inspection of the prior art systems, there remains a need for a compact, bloodless catheterization system which provides an early visual indication of flashback, is readily mass produced, easily packaged and sterilized and convenient for use preferably in a one hand operation. In such design, it would be highly desirable for the user to be able to see the flashback as soon as it enters the introducer needle to provide a prompt indication of the proper placement of the introducer needle into the vessel as the first step in the placement of the over-the-needle catheter into the vessel with the aid of a wire guide.